To modify elements by symmetry elements in the Main Menu select Model -> Operation -> Perform Symmetry.
Arguments:
The dialogue box to modify elements by point symmetry is:
Modify Elements by Point Translation
Arguments:
The dialogue box to modify elements by line symmetry is:
Modify Elements by Line Symmetry
Arguments:
The dialogue box to modify elements by plane symmetry is:
Modify Elements by Plane Symmetry
TUI command: Modify elements by symmetry